Practical drilling for oil and/or natural gas in most locations in the world that are now being explored requires use of a viscous liquid lubricant, which is generally called xe2x80x9cdrilling mudxe2x80x9d or simply xe2x80x9cmudxe2x80x9d by those who use it, and the word xe2x80x9cmudxe2x80x9d when used below in this specification shall be understood to mean drilling mud unless expressly stated to the contrary or required by the context. Mud normally is pumped continuously into and flows continuously out of a drill hole whenever drilling is underway. The mud flows into and out of the drill hole through separate passageways that insure that mud pumped into the drill hole must reach the near vicinity of the drill bit that is actually cutting a drill hole deeper during drilling before the mud can enter the passageway through which mud flows out of the drill hole during drilling. The mud serves to cool the drill bit and to remove from the drill hole soil and/or rock in the form of particles cut by the drill bit. If the cut rock and/or soil particles were not removed from the drill hole, these particles would eventually clog the drill bit and make continued drilling impossible.
A very large variety of physico-chemical compositions of mud are known in deep drilling (i.e., drilling to a depth greater than a few hundred feet below ground level). This variety is required in order to suit widely varying conditions of drilling. The particular class of mud to which this invention most particularly relates is characterized by containing organic materials, usually primarily petroleum-derived hydrocarbons, that constitute at least 50% of the total mass of the mud. This class of mud will usually be designated below in this specification as xe2x80x9creactivexe2x80x9d mud, a term of established use in drilling. Reactive mud usually also contains some water and one or more types of inorganic salts, and if the mud contains inorganic salts, it usually also contains a non-hydrocarbon organic dispersing agent in order to avoid separation of the mud into more than one bulk liquid phase, at least while the mud is being used. (To be a bulk liquid phase as that term is to be understood in this specification, a phase must exist as at least one large enough continuous volume to be visible with the naked eye, and that continuous volume itself must be visually uniform. Therefore, a liquid that is stably dispersed in another liquid can not be a bulk liquid phase except in very unusual instances when the two liquids have almost exactly the same density; otherwise, a volume of liquid large enough to be seen with the naked eye is also large enough to sink or rise through another liquid with which it is mixed.) As a result of these constituents of a reactive mud, the mixture of the reactive mud with soil or rock chips that emerges from the drill hole during drilling with a reactive mud is normally incapable of functioning as soil to sustain any plants as large as grasses and other plants that are effective in stabilizing soils against erosion. Furthermore, this mixture of reactive mud with soil and/or rock chips that emerges from deep drilling with a reactive mud is usually legally regarded as a pollutant that must be disposed of in accordance with regulations under one or more of the U.S. Resource Conservation and Recovery Act, Safe Drinking Water Act, and Clean Water Act. Other jurisdictions, including the individual U.S. states, have additional regulations. The volume of this pollutant is often large, so that legal disposal of it is often costly.
Deep drilling may be performed wherever oil (and/or some other valuable recoverable fluid and/or fluidizable mineral) is believed to underlie the earth""s surface, and the surface at many places where drilling is desired is not one on which humans can reasonably be expected to work regularly for as long a time as is required for deep drilling, most often because the surface has too large an angle of slope. It is therefore customary, when deep drilling is to be performed under a naturally sloping surface, to create by means of earth-moving machinery a level area of at least about one acre, this level area being called a xe2x80x9cdrilling padxe2x80x9d, that surrounds the surface end of the intended drill hole and provides accommodation for the workers and machinery needed for practical deep drilling. A drilling pad on a large steeply sloping surface therefore constitutes an unnatural plain that interrupts the natural slope. Such an unnatural plain is subjected to strong erosive action during rain, particularly heavy rain, by water that falls onto the upslope periphery of the plain from the natural surface and falls off the downslope periphery of the plain on to the lower natural surface. In fact, experience in deep drilling has shown that such an unnatural plain, if built as simply as has been described above, does not usually last as long as required for deep drilling in areas susceptible to frequent heavy rains. In such areas, it is therefore usual to surround the drill pad with a buffer zone several tens of feet in width, the buffer zone sloping downward from the drill pad, so that any anticipated volume of run-off water flow will be diverted around the drill pad. This stratagem, of course, simply transfers the erosive force from the drill pad to the buffer zone.
Even at drilling sites that do not have a sharp natural slope, the natural terrain is seldom if ever so nearly level that a drill pad is not built prior to drilling. While drill pads on other sites are not usually subjected to such strongly erosive forces as are drill pads on steeply sloping sites, almost any drill pad, or even any drilling site without a drill pad, is likely to require compliance with legal guidelines to reduce pollution and/or erosion problems that are generated by some part of the total activity required to successfully drill a deep well.
The surface of a drill pad, along with the surface of its buffer zone if it has one, almost inevitably becomes contaminated during deep drilling with hydrocarbons and/or other materials considered undesirable in most parts of the natural environment. Therefore, legal regulations in most places where deep drilling is done require some substantial mitigation of the danger of erosion from the area of a drill pad and its buffer zone if any after the completion of drilling, in order to reduce the danger of hydrocarbons and other pollutants being washed from such former drilling sites onto other land or into bodies of surface water by run-off from the former drilling site after natural rains.
Erosion from terrain of almost any shape, if the terrain has a surface of particulate matter such as soil or gravel, rather than of massive solid rock, can be considerably mitigated if the particulate surface of the terrain is made up of soil that is sufficiently fertile to support the growth of plants that reduce the tendency to erosion, from flows of fluids over the surface of the soil in which they grow, and such plants are growing on the soil. The presence of such plants, while useful on terrain of any shape, is particularly effective in reducing the otherwise high amounts of erosion likely from sharply sloping terrain that has a particulate surface. Essentially every drill pad has a particulate surface, because a drill pad by definition is an artificial construction, and it is much cheaper to move particulate matter than a slab of solid rock large enough to serve as an effective drill pad. Given a sufficient supply of fertile soil, the growth of erosion retarding plants on and around the area of a no longer used drill pad can readily be achieved by means already known in themselves, whether or not the terrain needs to be reconfigured to reduce erosion. Realistically, however, a sufficient supply of fertile soil is rarely ever available naturally in the near vicinity of a no longer used drill pad, particularly when the pad was built on a large sloping surface.
Accordingly, one major objective of this invention is to provide a practical method for reducing erosion from areas of land in which substantial, erosion-promoting alterations of the natural terrain have been made for economic reasons. An alternative objective of the invention is to provide a practical method for remediating mixtures of petroleum hydrocarbons with particulate rock or soil so that substantially the entirety of such mixtures as remediated becomes fertile soil that is capable of supporting the growth of plants that reduce the likelihood of erosion of soil in which the plants grow. Other alternative, concurrent, and/or more detailed objectives will become apparent from the detailed description below.
It has been found that infertile mixtures of petroleum hydrocarbons with particulate rock or soil can be converted to fertile soils by
commingling these infertile mixtures with at least one of:
(I) nitrogenous, non-petroleum-derived organic matter and water in controlled proportions; and
(II) at least one material selected from the group consisting of the oxides, hydroxides, and carbonates of calcium, and the oxides, hydroxides, and carbonates of magnesium, and mixtures of any two or more thereof; and
(III) composting the resultant commingled materials under conditions such that the surfaces of the particles of the particulate rock or soil are accessible to the natural atmosphere.
The fertile soil thus produced, or fertile soil from other sources, can be effectively used to reduce the erosion potential of unnaturally created terrain by placement of the fertile soil in suitable areas and causing erosion-retarding plants to grow on the outer surface of the placement areas.